In conventional electromagnetically operable fuel injectors for intake manifold injection, a valve tube is formed from three parts as the main body of the fuel injector. A core and a valve seat carrier are connected to one another in a hydraulically sealed way via a nonmagnetic interface, at least two joints and connection points being necessary.
A fuel injector, in which the number of the components of the valve tube is decreased, so that the number of the connection points and joints is also reduced, is described in German Patent Application No. DE 195 03 821 A1. The entire valve tube is manufactured from a magnetically conductive material, so that magnetically nonconductive interfaces may be dispensed with. This design of the housing is not suitable for many applications in the case of direct fuel injection, since it is too short with respect to the existing installation situation and may not be sufficiently sealed against the engine compartment in a receptacle hole of a cylinder head.
A fuel injector is described in German Patent Application No. DE 101 03 932 A1, which is suitable in particular for the direct injection of fuel directly into the combustion chamber of an internal combustion engine, usage particularly being possible in installation situations in which a very long receptacle hole for the fuel injector is provided in the cylinder head. The fuel injector includes a nozzle body, which forms a housing body with an external pole and a coil housing, a solenoid coil, which is electrically excitable via a line and a plug contact, and a central fuel supply. The electrical line and the central fuel supply are jointly situated in an adapter, which substantially lengthens the fuel injector, and which is pluggable onto an inlet-side end of the housing body and connectable thereto. The fixed connections of adapter and housing body are achieved by welding, the components to be connected abutting one another. In particular, in the case of great lengths of the adapter, the risk of a negative alignment error exists during the joining and laser welding if the planar surfaces are not exactly perpendicular to the component axis. Possible centering of the components to avoid such alignment errors may have the result that wedge-shaped gaps arise at the contact surfaces. This results in problems during welding or in excessive welding warpage because of an irregular gap over the circumference of the joint.